1. Technical Field
The present invention relates to an information recording and reproduction apparatus which records and reproduces various kinds of information on and from a magnetic recording medium using spot light obtained by a condensing light beam.
2. Background Art
In recent years, the recording density of the information within a single recording surface has been increasing with increases in the capacity of a hard disk or the like in a computer apparatus. For example, in order to increase the recording capacity per unit area of a magnetic disk, it is necessary to increase the surface recording density. However, as the recording density increases, the recording area per bit occupied on a recording medium decreases. If the bit size is reduced, the energy of the 1-bit information becomes close to heat energy at room temperature. As a result, a problem of thermal demagnetization occurs. For example, the recorded information is reversed or lost due to thermal fluctuation or the like.
An in-plane recording method generally used is a method of performing magnetic recording such that the direction of magnetization faces an in-plane direction of a recording medium. In this method, however, loss of the recording information by thermal demagnetization described above and the like easily occur. Therefore, in order to solve such a problem, there is a shift to a perpendicular recording method which records a magnetization signal in a vertical direction with respect to a recording medium. This method is a method of recording the magnetic information on a recording medium under the principle of bringing single poles close to each other. According to this method, the recording magnetic field faces an almost vertical direction with respect to a recording layer. Since it is difficult for an N pole and an S pole to make a loop within a recording layer surface, the information recorded in a vertical magnetic field tends to maintain the stability in terms of energy. For this reason, this perpendicular recording method is stronger against the thermal demagnetization as compared to the in-plane recording method.
However, in recent years there has been a demand for recording media to have a higher density according to the need for the recording and reproduction of a larger amount of information with higher density. Accordingly, in order to suppress to a minimum an influence between adjacent magnetic domains or thermal fluctuation, recording media with strong coercivity have started to be adopted. For this reason, even in the perpendicular recording method described above, it has been difficult to record the information on a recording medium.
Therefore, in order to solve this problem, there is provided a hybrid magnetic recording method of temporarily reducing the coercivity by locally heating a magnetic domain using spot light, which is obtained by condensing light beam, or near-field light, which is obtained by condensing light beam, and performing writing in the meantime. In particular, when using near-field light, it becomes possible to treat the optical information in a region with a wavelength of light or less, which was not possible in a conventional optical system. Consequently, it is possible to realize high density of recording bits exceeding conventional optical information recording and reproduction apparatus and the like.
Various items are provided as information recording and reproduction apparatuses based on the hybrid magnetic recording method described above. As one of them, there is known an information recording and reproduction apparatus capable of realizing reproduction and recording with super-high resolution, high-speed recording and reproduction, and a high S/N ratio by generating sufficiently large near-field light from a fine aperture by supplying light for generating near-field light to a near-field light head.
As this information recording and reproduction apparatus, there is known a configuration which includes a driving arm (carriage), which can angle-oscillate around a pivot bearing shaft by a voice coil motor (VCM) or the like, and in which a slider provided with a near-field light head is fixed to a distal end of the driving arm. This slider includes a unit substrate bonded to an opposite surface to an ABS-side surface (floating surface) of the slider, that is, an upper surface of the slider, a light source provided on the unit substrate, a propagation layer which is provided on an element forming surface of the unit substrate and which includes an optical path of light emitted from the light source, and a lens section which is provided in the propagation layer in order to adjust propagation of the light emitted from the light source, as disclosed in Patent Citation 1, for example.
The information recording and reproduction apparatus described above disposes the slider at the desired position on a disk by making the slider perform scanning on the disk by moving the driving arm around the pivot bearing shaft. Then, the near-field light emitted from the light source and the recording magnetic field generated from the slider are made to cooperate with each other so that the information can be recorded on the disk. In addition, the ABS of the slider is configured to float such that when air pressure is applied to the slider by the undulation of a disk or the like, it follows the air pressure.